Detonator

ABSTRACT

An electronic detonator (1) which comprises an ignition charge, a battery unit (19) for emitting igniter current for initiating the ignition charge, and an electronic circuit (4) for controlling said emission of igniter current. The battery unit (19) is movable in the detonator between a resting position and an activated position, in which the battery unit is connected to emit said igniter current. Battery activating means (25, 28) are provided, in response to external activation (3), for pyrotechnically causing the battery unit (19) to move from the resting position to the activated position.

TECHNICAL FIELD

The present invention relates to an electronic detonator adapted forcivil use of the type which comprises an ignition charge, a battery unitfor emitting igniter current for initiating the ignition charge and anelectronic circuit for controlling said emission of igniter current.

TECHNICAL AREA

Electronic detonators which have been proposed up to the present aregenerally adapted to use, as an igniter current emitting means, acurrent storing means, such as a capacitor, which before initiating theignition charge is charged by means of current that is supplied via thecontrol lines (often a two-wire bus) to which the detonator is connectedand by which detonator set-up signals and detonator firing signals arecommunicated. If the detonator has a built-in battery, for instance, todrive the electronics of the detonator, it has been deemed to be mostessential that the capacity or energy content of the battery does notallow emission of current which could initiate the ignition charge evenif, for unknown reasons, current paths required therefor would beprovided.

A “nonelectrical” detonator has been suggested (see WO 96/04522) whichis activated via a so-called ignition or shock tube and which comprisesa battery for emitting igniter current for initiating an ignitioncharge, the battery either being active and connected by means of aswitch which is acted upon by the pressure generated by the burningignition tube in the detonator, or alternatively being connected butwill be activated, for instance thermally, by action from the burningignition tube.

However, those skilled in the art would realise that using a switch oractivating a battery as stated above generally means uncertainty in thepresent context and can easily result in an undesirable current supplywith the ensuing uncontrollable detonation.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an electronicdetonator which is provided with a battery, whereby the risks ofuncontrollable initiation of the ignition charge of the detonator as aresult of non-intended battery current supply are, in practice,completely eliminated.

The above-mentioned object is achieved by means of an electronicdetonator which exhibits features according to the invention which areevident from the appended claims.

The invention is thus based on the understanding that primarily batteryconnection must not take place by switch-controlled connection orexternally provided activation of a battery, but by an active batteryunit (consisting of one or more active cells), in the following referredto as “battery”, being caused to move inside the detonator to a positionwhere igniter current can be emitted. Suitably, it is a matter of thebattery being caused to move between a resting position, in whichigniter current cannot be taken out of the battery, to an activatedposition, in which the battery is prepared to emit igniter current. Themotion of the battery is conditioned by the action of mechanical forcesexerted on the battery, which has to be of a predetermined magnitude andhas a predetermined direction in order to overcome a strong inertia ofmotion of the battery. These parameters of action may be chosen so thatonly desirable, expected action of forces causes motion of the batterywhile overcoming said inertia of motion of the battery, while othersorts of uncontrolled action owing to shock, acceleration and similarrough treatment, as well as action caused by static electricity andelectric and magnetic fields do not cause any motion of the battery and,consequently, any risk of undesirable battery connection.

Suitably, the detonator according to the invention comprises batteryactivating means which are adapted to provide, in response to externalactivation, such as by means of an ignition tube or electric controlsignals, the required application of forces on the battery. Saidactivating means preferably operate pyrotechnically. Advantageously, useis made of a drive or propellant charge which is arranged in thedetonator and is releasable in a controlled manner and which inconnection with combustion generates such a pressure that the desiredapplication of forces is obtained. The drive charge can be releasedelectrically or by means of an ignition tube. It is also possible towork without a drive charge, in which case the pressure of the gaseswhich are generated in connection with the combustion of the ignitiontube charge is used to generate the required driving pressure inside thedetonator.

When using a drive charge, it is advantageously arranged in a drivechamber, to which an actuation part of the battery is exposed to beacted upon so as to cause movement by means of a driving pressure whichis generated in the drive chamber by the drive charge. When an ignitiontube is used, it is suitable to arrange a non-return valve at theconnection of the ignition tube to the drive chamber in order to preventthe driving pressure generated in the drive chamber from beingdischarged via the ignition tube.

The battery is advantageously given the shape of a plunger or pistonwhich is arranged in a corresponding bore in the detonator. In thisconnection, it is preferred for the bore to be arranged in a tubularelement which is dimensionally stable and resistant to mechanical actionand which has a longitudinal extension at least corresponding to thelongitudinal extension of the battery and the distance of motion of thebattery between a resting position and an activated position as well asa preferred free space in front of the front end of the battery (seen inthe direction of motion), when the battery has moved to the activatedposition.

Since detonators conventionally are elongated and have an ignitioncharge in one end, it is suitable that the axial direction of saidtubular element is parallel to and preferably coincides with thelongitudinal axial direction of the detonator.

When using a drive chamber, it is suitably aligned with the bore in atubular element according to the above, preferably constituting anextension thereof.

Constructively, the tubular element and the drive chamber areadvantageously formed as a pressure vessel in order to be able to resista predetermined pressure which in any case exceeds the driving pressurerequired to cause the battery to move from a resting position to anactivated position. At the same time, a very stable and resistantconstruction is obtained, as is appreciated, the construction having agreat capacity of resisting rough treatment, especially in thetransverse direction, which otherwise could possibly involve a risk ofuncontrolled change as regards motion of the battery.

The motion of the battery from a resting position to the activatedposition preferably occurs towards the ignition charge. Thus, improvedsafety is obtained in connection with uncontrolled axial action due toacceleration (transverses action due to acceleration constitutes, asthose skilled in the art realise, no risk). Action due to accelerationwhich should be able to cause “forward” motion of the battery towardsthe ignition charge must in principle mean an impact in the longitudinaldirection of the detonator on the end of the ignition charge of thedetonator or, alternatively, “backward” jerks in the opposite end of thedetonator. In the first case, the ignition charge will detonate due tothe impact itself a long time before the battery starts moving towardsthe activated position. In other words, here it is not a matter of anyadditional risks. In the second case, with “backward” jerks, it is inpractice almost impossible to bring about such a powerful longitudinalacceleration of the detonator that the battery will be caused to moveforwards to the activated position. If an ignition tube or the like isconnected to the associated end of the detonator, it may also beadvantageous to make the connection to the detonator in such a mannerthat in connection with jerks, for instance, in the ignition tube, theignition tube or its fixing in the detonator breaks well before thedetonator has been subjected to hazardous acceleration.

As mentioned above, it is essential that the battery should not moveeasily, but exhibit the required inertia of motion. According to theinvention, preferably this inertia is dependent on friction, that is thebattery is movable from its resting position to its activated positionagainst the action of a frictional force, in a wide sense. Preferably,the frictional force is adapted to increase from a significant startingvalue, after the battery has moved, during acceleration, an initialdistance from the resting position. Stopping the battery in itsactivated position advantageously takes place by the frictional forcethere being adapted to be further increased, possibly in combinationwith motion-stopping deformation and/or penetration work in connectionwith the battery being contacted to allow delivery of current.

The frictional force mentioned above can, when the battery moves as apiston in a bore, be ensured by means of adaptation of the diameterand/or special friction-generating elements, such as projections, ribelements or the like, on the bore wall and/or the bore facing surface orcircumferential surface of the battery.

In order to allow current supply from the battery, its two poles have tobe contacted with suitable current conductors. According to theinvention, the two poles of the battery are advantageously not contacteduntil the battery is approaching or has reached its activated position.In their non-contacted position, the poles of the battery are preferablyinsulated or encapsulated, advantageously by the entire battery in itsresting position being encapsulated in an insulated fashion.

In a preferred embodiment, the battery has at least one contact terminalwhich in a non-activated position of the battery is coated withinsulation and which in the activated position of the battery is adaptedto be penetrated by a co-operating contacting means in the detonator. Itis especially preferred that the battery on its front end side should beprovided with a contact terminal which is coated with insulation andwhich is adapted to be contacted, when the battery is in its activatedposition, by a contact pin which penetrates the insulation and isarranged in the bore for the battery.

Preferably, the contacting of the two poles of the battery takes placeat essentially separated locations, so that the number of conditionsrequired for the contacting is increased.

In the preferred embodiment, thus a second contact terminal coated withinsulation is arranged on the bore side of the battery, a co-operatingcontacting means being arranged protruding in the bore, so that, whenthe battery is in the activated position, the contacting meanspenetrates the insulation of the contact terminal and is in contact withthe contact terminal.

With a view to further increasing the safety as regards uncontrolledconnection of the battery, an independent contact arrangement or switcharrangement can be arranged in a line circuit for emitting ignitercurrent from the battery, the contact arrangement being open in a stateof rest and closed in an activated state, the contact arrangement beingadapted to be moved from the state of rest to the activated state inresponse to the external activation. Said arrangement is advantageouslyadapted to be affected by the driving pressure which is generated to acton the battery.

A doubled battery connecting system of the above type is especiallyadvantageous when the direction of motion of the battery from theresting position to the activated position and a direction of motion ofthe contact arrangement when passing from the open to the closed stateare essentially separated, preferably at least essentially opposite oressentially orthogonal. As will be appreciated, this means that in allprobability uncontrolled action due to acceleration can in any case onlyprovide one of the two connecting functions required for current supplyfrom the battery.

In the following, the invention will be described in more detail by wayof non-limiting examples with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic longitudinal section of a part of an electronicbattery with an ignition tube connected at the rear end thereof, thedetonator comprising a battery function in a resting position inaccordance with an embodiment of the present invention.

FIG. 2 is a schematic cross-section along the line A—A in FIG. 1.

FIG. 3 is a schematic longitudinal section as in FIG. 1, the batterybeing moved to an activated position.

FIG. 4 is a schematic longitudinal section of the same type as in FIG. 1regarding another embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

FIGS. 1 and 2 schematically illustrate an embodiment of an electronicdetonator in accordance with a first embodiment of the presentinvention. The basic design of the detonator, which is generallydesignated 1, is completely conventional since it has an elongatedcylindrical shape with an external sleeve 2 of aluminium, at the rearend of which a pyrotechnic ignition tube 3 (such as a NONEL® tube) isconnected in a conventional manner. Inside the sleeve, an ordinaryelectronic circuit 4 is arranged. This circuit can in any suitable waycontrol the detonation delay of the detonator, which comprises controlof the final closing of the current path in order to bring aboutdetonation. An ignition charge is also conventionally arranged in thefront end of the detonator, which for the sake of clarity is not shownin FIG. 1. For detonation of the ignition charge the necessary currentsignals are fed from the circuit 4 to the ignition charge via wires 5.

In connection with the rear connection of the ignition tube 3, acontrollable current supply device is arranged inside the sleeve 2. Thecurrent supply device comprises a cylindrical casing element configuredas a pressure vessel which is designed in a very stable manner asregards shape and resistance and consists of two axially joined steeltubular elements 6 and 7. The front tubular element 6 has acircular-cylindrical bore 8 and is closed in front by means of a steelplug 9 which is fixed to the end of the bore. The front end of thetubular element 6 encompasses and further secures the plug 9, as shownat 10, a central opening 11 giving access to the plug 9. A pointedcontact pin 12 of steel is fixed centrally in the plug. The pin 12 iselectrically insulated from the plug 9 by means of enclosing insulation13 and electrically connected to the circuit 4 via a first currentsupply wire 14. A second current supply wire 15 to the circuit 4 issuesfrom the tubular element 6. The pointed part of the pin 12 pointsbackwards and extends axially into the bore 8.

In the front part of the bore 8, four longitudinal ribs 17 are uniformlydistributed on the bore wall. The ribs extend from the plug 9 andbackwards in the bore 8 over about half the length of the bore. The ribsare essentially triangular in cross-section and are ramp-shaped at theirrear end and successively increasing at their front part connecting withthe plug 9. The function of the ribs 17 will be described below.

In the bore 8 a battery 19 is arranged in the form of a completelyencapsulated battery unit consisting of three battery cells 20 axiallyconnected in series. The encapsulation 21 is made of electricallyinsulating material, such as plastic, and gives the battery essentiallythe shape of an ammunition bullet, the diameter of which is adapted tothe diameter of the bore 8, so that the fit almost is to be consideredas a force fit, whereby the battery 19 is movable in the bore 8 onlywith great inertia, that is against the action of an essentialfrictional resistance. The front end of the battery is rounded andincludes an axial embedded first battery pole contact terminal 22. Asimilarly insulated embedded second battery pole contact terminal 23consists of a copper ring which encompasses the rearmost battery celland is arranged somewhat below the circumferential or bore facingsurface of the battery. The rear end face 24 of the battery extendstransversely to the axial direction of the battery and the bore andconstitutes a driving surface, that is a surface which is designed forapplying driving force to the battery.

The rear tubular element 7 defines a similar circular-cylindrical drivechamber 25 which constitutes an extension of the bore 8, although with asomewhat reduced diameter. The ignition tube 3 is fixed to the rear endof the tubular element 7 in an axial duct 26 which leads into the drivechamber and whose drive chamber end constitutes a seat for a ball of anon-return valve which is arranged in the drive chamber. A drive charge28 is arranged in the drive chamber and can be ignited by means of theignition tube 3.

In FIG. 1, the detonator is illustrated in a basic state, that is anon-discharged state, the battery 19 being in a resting position at therearmost end of the bore 8 with its rear driving surface 24 in directconnection with the drive chamber 25. When the detonator is to be madeto detonate, the burning ignition tube 3 will ignite the drive charge 28in the drive chamber 25, exhaust gases being quickly developed, whichincreases the pressure in the drive chamber. The considerably increasedpressure moves the ball 27 of the non-return valve into sealing abutmentagainst the duct 26 and drives the battery forwards to an activatedposition. The state thus obtained is illustrated in FIG. 3.

Initially, the battery is accelerated by the driving pressure andagainst the action of the resistance as a result of the friction betweenthe bore well and the circumferential surface of the battery up to ahigh speed which typically may be in the order 100 m/s or more. Afterhaving moved about half its distance of motion, the battery contacts theribs 17, the frictional resistance increasing significantly by the ribspenetrating into the plastic encapsulation 21. When the batteryapproaches its end position of motion, it is stopped as a consequence offurther resistance caused by the enlarged front ends of the ribs 17 andthe contacting process. This process consists of, on the one hand, thepin 12 penetrating the front end encapsulation of the battery andcontacting the pole terminal 22 of the battery, and, on the other hand,the rear end parts of the ribs 17 penetrating the side encapsulation ofthe battery into contact with the copper ring 23. In other words, thebattery is in this position connected to the electronic circuit 4 viathe wire 14, which is in contact with the battery pole 22 via the pin12, and via the wire 15 which is in contact with the battery pole 23 viathe wall of the tubular element 6 and the steel ribs 17 which areelectrically connected thereto.

It will be noted that in the activated position shown in FIG. 3 thefront end of the battery is not in contact with the plug 9, but in frontof the battery remains a small free bore space 31. This space allowsreceiving of the compressed air which forms in front of the battery whenthis is driven from its resting position to its activated position. Thiscompression promotes stopping of the battery.

FIG. 4 illustrates a modification of the detonator according to FIGS.1-3, in which a supplementary safety function has been arranged in theform of a separate switch arrangement which is detached from the motionof the battery. This is arranged in the wall of the drive chamber and isaffected by the driving pressure which is generated in the drive chamberwhen initiating the detonator. In the following, only the modificationswhich have been made in relation to the embodiment according to FIGS.1-3 will be described in more detail.

The combination of the tubular elements 6 and 7 is in this caseelectrically insulated from the external sleeve 2 by means of aninsulation 33. One current supply wire 15 of the electronic circuit 4 ishere connected to the electrically conductive external sleeve 2 insteadof to the tubular element 6 as in FIG. 1. In order to achieve controlledclosing of a current path between the external sleeve 2 and the tubularelements 6, 7, a contact element 37 is movably arranged in the wall ofthe drive chamber, so that closing takes place when the driving pressurein the drive chamber drives the contact element radially outwards topenetrate the insulation 33 and to electric contact with the externalsleeve 2. The contact element 37 is made of conductive steel materialand is in electrically conductive, although movable, contact with thewall of the drive chamber in the recess 38 which is formed therein andadapted to the contact element. The through recess 38 has an outer partwith a reduced diameter, in which a pointed part of the contact elementis fitted, and an inner cylindrical part in which a piston part of thecontact element is insertable with a fit. The fit of the contact element37 in the recess 38 is such that a considerable driving pressure isrequired in the drive chamber for overcoming a resistance of motion ofthe contact element. Thus, it is ensured that a connection-generatingmotion of the contact element 37 cannot take place as a result ofundesirable or uncontrolled action applied to the detonator as discussedabove regarding the motion of the battery.

It will be appreciated that the fact that the battery 19 and the contactelement 37 have to move in directions which are perpendicular to oneanother essentially decreases the risk of uncontrolled closing of thecurrent paths between the battery and the electric circuit.

The following is given as very general examples of parameters concerninga detonator which includes the present invention.

diameter of the external sleeve: about 6.5 mm diameter of the bore:about 3 mm wall thickness of the bore tubular element: about 1 mmfrictional force which the battery has to overcome: several tens of kpweight of the battery: about 0.5 g distance of motion of the battery:about 10 mm time for the motion of the battery from the resting about0.1 ms position to the activated position: driving force on the drivingend face of the battery: about 1500 kp total weight of the detonator:about 15 g

Given these conditions, it is possible to estimate that the battery canbe exposed to an axial acceleration in the order of tens of thousands Gwithout the battery moving to the activated position. This means, aswill be appreciated, an extraordinarily high degree of safety.

If an additional contact function, for instance in accordance with thatillustrated in FIG. 4, is used, the safety as regards uncontrolledinitiation will be improved, so that the requirements as to resistanceto motion and capacity of resisting axial acceleration of the batterycan be decreased. Thus, it is possible to reduce the amount of drivecharge and work at lower pressure in the drive chamber, which, in itsturn, reduces the requirements as to the pressure-vessel-like tubularelement construction. Wall thicknesses that are thus decreased allowlarger diameters of the battery, which facilitates the choice of type ofbattery.

What is claimed is:
 1. An electronic detonator comprising an ignitioncharge, a battery unit for emitting igniter current for initiating theignition charge, an electronic circuit for controlling the emission ofigniter current, and a flexible pyrotechnic shock tube, the battery unitbeing per se operative to emit igniter current and being movable in thedetonator between a resting position, where the battery unit iselectrically separated from the electronic circuit, and an activatedposition, where the battery unit is electrically connected to theelectronic current, and battery moving means being provided, in responseto external activation by the flexible pyrotechnic shock tube, forpyrotechnically causing the battery unit to move from the restingposition to the activated position whereafter ignition current forinitiating the ignition charge is emitted after a predetermined timedelay controlled by said electronic circuit, wherein the battery unithas the shape of a plunger or piston and is arranged in a correspondingbore in the detonator, the bore being arranged in a tubular elementwhich has a longitudinal extension essentially corresponding to alongitudinal extension of the detonator, the battery unit being movablein the bore from its resting position to its activated position againstthe action of a frictional force.
 2. A detonator as claimed in claim 1,wherein the pyrotechnic shock tube is connected to the detonator.
 3. Adetonator as claimed in claim 1, wherein the battery activating meanscomprises a drive charge for the battery unit, the drive charge beingarranged in the detonator.
 4. A detonator as claimed in claim 3, whereina pyrotechnic shock tube connection is provided at the drive charge. 5.A detonator as claimed in claim 3, wherein the drive charge is arrangedin a drive chamber, to which an actuation part of the battery unit isexposed to be acted upon so as to cause movement by means of a drivingpressure which is generated in the drive chamber by the drive charge. 6.A detonator as claimed in claim 5, wherein the drive chamber is arrangedin a tubular element extension aligned with the bore.
 7. A detonator asclaimed in claim 5, wherein the tubular element and the drive chamberhave walls formed as a pressure vessel in order to resist apredetermined driving pressure.
 8. A detonator as claimed in claim 1,wherein the bore in the detonator is formed in such a manner that, whenthe battery unit is in its activated position, a free space remains infront of the battery unit, in which gas pushed forward by the batteryunit can be compressed.
 9. A detonator as claimed in claim 1, furthercomprising a contact arrangement in a line circuit for emitting ignitercurrent from the battery unit, the contact arrangement being open in astate of rest and closed in an activated state, the contact arrangementbeing adapted to be moved from the state of rest to the activated statein response to the pyrotechnic activation.
 10. A detonator as claimed inclaim 9, wherein a direction of motion of the battery unit from theresting position to the activated position and a direction of motion ofthe contact arrangement when passing from an open to a closed state aresubstantially separated, at least essentially opposite or essentiallyorthogonal.
 11. A detonator as claimed in claim 1, wherein the motion ofthe battery unit from the resting position to the activated positionoccurs toward the ignition charge, the distance of motion being at leastabout 1 cm.
 12. A detonator as claimed in claim 1, wherein the batteryunit, in its resting position, is completely encapsulated in anelectrically insulated fashion.
 13. An electronic detonator comprisingan ignition charge, a battery unit for emitting igniter current forinitiating the ignition charge, and an electronic circuit forcontrolling the emission of igniter current, the battery unit beingmovable in the detonator between a resting position and an activatedposition, in which the battery unit is connected for emitting theigniter current in a controlled way, and battery activating means beingprovided, in response to external activation, for pyrotechnicallycausing the battery unit to move from the resting position to theactivated position, wherein the battery unit has the shape of a plungeror piston and is arranged in a corresponding bore in the detonator, thebore being arranged in a tubular element which is dimensionally stableand resistant to mechanical action and which has a longitudinalextension essentially corresponding to a longitudinal extension of thedetonator, the battery unit being movable in the bore from its restingposition to its activated position against the action of a frictionalforce, wherein the battery activating means comprises a drive charge forthe battery unit, the drive charge being arranged in the detonator;wherein the drive charge is arranged in a drive chamber, to which anactuation part of the battery unit is exposed to be acted upon so as tocause movement by means of a driving pressure which is generated in thedrive chamber by the drive charge; wherein a non-return valve isarranged at an ignition tube connection to the drive chamber in order toprevent driving pressure generated in the drive chamber from beingdischarged via the ignition tube connection.
 14. An electronic detonatorcomprising an ignition charge, a battery unit for emitting ignitercurrent for initiating the ignition charge, and an electronic circuitfor controlling the emission of igniter current, the battery unit beingmovable in the detonator between a resting position and an activatedposition, in which the battery unit is connected for emitting theigniter current in a controlled way, and battery activating means beingprovided, in response to external activation, for pyrotechnicallycausing the battery unit to move from the resting position to theactivated position, wherein the battery unit has the shape of a plungeror piston and is arranged in a corresponding bore in the detonator, thebore being arranged in a tubular element which is dimensionally stableand resistant to mechanical action and which has a longitudinalextension essentially corresponding to a longitudinal extension of thedetonator, the battery unit being movable in the bore from its restingposition to its activated position against the action of a frictionalforce, wherein the frictional force is adapted to increase after thebattery unit has moved an initial distance from the resting position.15. A detonator as claimed in claim 14, wherein the frictional force isadapted to successively increase to stop the motion of the battery unitat the end of the motion process.
 16. An electronic detonator comprisingan ignition charge, a battery unit for emitting igniter current forinitiating the ignition charge, and an electronic circuit forcontrolling the emission of igniter current, the battery unit beingmovable in the detonator between a resting position and an activatedposition, in which the battery unit is connected for emitting theigniter current in a controlled way, and battery activating means beingprovided, in response to external activation, for pyrotechnicallycausing the battery unit to move from the resting position to theactivated position, wherein the battery unit has the shape of a plungeror piston and is arranged in a corresponding bore in the detonator, thebore being arranged in a tubular element which is dimensionally stableand resistant to mechanical action and which has a longitudinalextension essentially corresponding to a longitudinal extension of thedetonator, the battery unit being movable in the bore from its restingposition to its activated position against the action of a frictionalforce, comprising friction generating elements on a bore wall and/or abore facing surface of the battery unit.
 17. A detonator as claimed inclaim 16, wherein the friction generating elements comprise projectionson the bore wall for engaging with the bore facing surface of thebattery unit.
 18. A detonator as claimed in claim 17, wherein theprojections comprise rib elements which extend parallel to a directionof motion of the battery unit.
 19. A detonator as claimed in claim 18,wherein the projections from the bore wall have an increased height at abattery unit activating end of the bore.
 20. A detonator as claimed inclaim 16, wherein the motion-counteracting frictional force is adaptedto prevent motion of the battery unit to the activated position inconnection with action due to acceleration in a direction of motion, atleast up to a predetermined level.
 21. An electronic detonatorcomprising an ignition charge, a battery unit for emitting ignitercurrent for initiating the ignition charge, and an electronic circuitfor controlling the emission of igniter current, the battery unit beingmovable in the detonator between a resting position and an activatedposition, in which the battery unit is connected for emitting theigniter current in a controlled way, and battery activating means beingprovided, in response to external activation, for pyrotechnicallycausing the battery unit to move from the resting position to theactivated position, wherein the battery unit has the shape of a plungeror piston and is arranged in a corresponding bore in the detonator, thebore being arranged in a tubular element which is dimensionally stableand resistant to mechanical action and which has a longitudinalextension essentially corresponding to a longitudinal extension of thedetonator, the battery unit being movable in the bore from its restingposition to its activated position against the action of a frictionalforce, wherein the battery unit has at least one contact terminal whichin a non-activated position of the battery unit is coated withinsulation and which in the activated position of the battery unit isadapted to be penetrated by a cooperating contacting means in thedetonator.
 22. A detonator as claimed in claim 21, wherein a contactterminal which is coated with insulation is arranged on a bore side ofthe battery unit and wherein a co-operating contacting means is arrangedprotruding in the bore, so that when the battery unit is in theactivated position, the contacting means penetrates the insulation ofthe contact terminal and is in contact with the contact terminal.
 23. Adetonator as claimed in claim 21, wherein the contacting means isincluded in friction generating elements on a bore wall.
 24. A detonatoras claimed in claim 21, wherein the battery unit has a front end sideprovided with a contact terminal which is coated with insulation andwhich is adapted to be contacted, when the battery unit is in itsactivated position, by a contact part which penetrates the insulationand is arranged in the bore.